1. Field of the Invention
This invention relates to jigs and guides for holding crown molding and guiding a saw to cope it.
2. Description of Prior Art
Crown molding is a strip of wood placed around the intersection between the walls and the ceiling of a room. At each corner of the room two molding strips meet at a joint that appears like the corner of a picture frame. However, the construction of this joint is not a simple 45-degree miter like a picture frame. Since the corners of a room are often not perfectly square, a simple 45-degree miter would sometimes show a gap in the joint. In addition, crown molding is often a flat strip that leans between the wall and the ceiling at a characteristic angle, unlike the molding of a picture frame.
A method of producing joints with a clean appearance in this type of molding is called coping. A first molding strip is attached along the intersection of a wall and ceiling, and its end abuts the adjacent wall. The adjoining end of a second molding strip is cut to match the contours of the first molding strip and abuts the first molding strip. Contouring the end of the second molding strip is called coping. This can be done manually with a coping saw, which has a thin blade spanning the ends of a U-shaped frame with a handle. However this is slow, difficult, and requires high skill and manual dexterity.
Numerous coping accessories and systems have been devised. However, these are often complex and expensive. They include complete powered table systems with jigs for crown molding, and hand-held power coping saws with guides for crown molding. One hand-held model (U.S. Pat. No. 5,388,334) is like a miniature band saw, having a thin endless blade that is driven around rollers in the U-shaped frame of the saw. It has guide rollers that hold the saw at a selected angle to the molding, and follow its contours. Another hand-held model (US5819420) is a jigsaw with an attached rounded guide plate that allows the saw to be held at any desired angle on the molding. These do not provide firm support of the molding.
Powered table systems include U.S. Pat. No. 5,667,001, U.S. Pat. No. 6,006,641, U.S. Pat. No. 536,732, U.S. Pat. No. 429,446, and U.S. Pat. No. 5,136,904. Each of these provides a table with a jig for holding the coping, and a movable frame mounted on the table holding a power saw that follows the contour of the coping. These are complex compared to the present invention.
The main objective of this invention is provision of an inexpensive molding jig and a method for coping crown molding with a standard miter saw and a jigsaw that produces professional results with minimal training and skill.
This objective is met with a two-step method using a standard miter saw to make a first crosscut, and an inexpensive jig that holds crown molding and guides a hand-held jigsaw in a coping operation. The jig has a horizontal base plate 1 and two vertical side fences 2A, 2B. A guide plate 3 is attached between the front ends of the fences, and is spaced from the base plate by a gap 5. The guide plate is oriented as if rotated through two particular angles about two respective axes from a position normal to the fences and base plate. The resulting front surface of the guide plate guides a jigsaw in the coping process. An opening 4 in the guide plate is aligned with the upper surface of the base plate, and allows molding to be placed on the base plate with an end in the opening to interfere with the jigsaw blade at a desired coping angle. First, the molding is placed inverted against a miter saw fence, and an end of the molding is cut at a 45-degree angle. Next the molding is placed in the jig, with the cut end in the opening of the guide plate. A jig saw is placed on the front surface of the guide plate, and the operator manually guides the jigsaw to follow the contour of the front surface of the molding along the miter cut line. This produces a coped end resulting in a clean 90-degree joint in crown molding.